It is known in the art to have a vehicle, such as a bus, with a drive assembly powered by a traction motor. It is also known in the art to combine an internal combustion engine with a generator to produce a DC voltage that is stored in a battery or batteries. The voltage of the DC battery or batteries is inverted by an inverter into an AC signal which is provided to the traction motor. This arrangement allows the engine to constantly operate at its most efficient speed.
The engine, the inverter and the traction motor all generate heat. It is therefore necessary to equip the vehicle with a heat exchange system to remove a substantial portion of the heat generated by the engine, the inverter and the traction motor from the vehicle.
One way in which the heat can be removed is by equipping the vehicle with a single core radiator and a single heat exchange circuit in fluid communication with the single core radiator and in heat exchange relationship with the engine, the inverter and the traction motor. However, to protect the inverter, it is necessary to keep the operating temperature of the coolant in heat exchange relationship with the inverter relatively low, approximately 70 C.
Given the low operating temperature required to protect the inverter, it would be necessary in such a system to reject a large amount of waste heat from the radiator at a relatively low temperature differential between the coolant and the ambient air. The size of a single core radiator required by the operating criterion described above would be probatively large when compared with the size of the vehicle on which the radiator would be mounted.